Multimedia receiver systems that employ multiple tuners have become increasingly popular in recent years. Certain types of these receiver systems, such as digital multimedia recorder systems, are capable of digitizing and storing audio and/or video content on hard drives which are currently between 5 and 100 Gbytes in size. Various types of multimedia recorders are available today including personal video recorders (“PVRs”), from companies such as Tivo™ and Sonicblue,™ which are capable of storing several hours of broadcast television programming; and digital music recorders such as the iPod™ from Apple Computer,™ which is capable of storing hundreds of hours of audio content copied from compact discs (“CDs”) or downloaded from the Internet.
A prior art PVR system for storing digital video and audio content is illustrated in FIG. 1. As illustrated, one or more tuners 120, 121 are configured to lock on to audio/video signals 100, 101 transmitted at specified carrier frequencies and down-convert the signals to baseband. Demodulators 130, 131 demodulate the baseband signals to extract the underlying digital data. If the audio/video signal is a cable signal, then the demodulators 130, 131 are typically Quadrature Amplitude Modulation (“QAM”) demodulators. If the audio/video signal is a satellite signal, then the demodulators 130, 131 are typically Differential Phase Shift Keying (“DPSK”) demodulators.
The demodulated signals are then transmitted to conditional access (“CA”) subsystems 140, 141 which prevent channels/content from being transmitted on the system which the user does not have the right to receive (e.g., subscription-based content such as HBO or pay-per-view channels). If the CA subsystems 140, 141 allow the user to view a particular channel then multimedia content (i.e., audio and/or video content) from the channel is transmitted over a system bus 151 (via bus interface 150) to a mass storage device 160. An MPEG-2 decoder module 170 coupled to the system bus 151 decodes/decompresses the multimedia content before it is rendered on a multimedia rendering device 135 (e.g., a television).
Prior art PVR systems may also utilize a main memory 126 for storing instructions and data and a central processing unit (“CPU”) 125 for executing the instructions and data. For example, the CPU may provide a graphical user interface displayed on the television, allowing the user to select certain television or audio programs for playback and/or storage on the mass storage device 160.
Multi-tuner receiver systems, such as the PVR system illustrated in FIG. 1, may be equipped with two sets of tuners, demodulators and CA subsystems and are therefore capable of concurrently receiving, decoding and, perhaps, storing multimedia content from two independent broadcast channels. In the case of a PVR system, for example, such a configuration is useful for recording one program (e.g., received by the first tuner 120), while watching another program (e.g., received by the second tuner 121). Frequently, however, when a user is simply browsing through channels, one (or more) of the tuners remains unutilized.
Accordingly, what is needed is a digital multimedia receiver system which takes advantage of at least one unused tuner to improve the speed with which the system tunes to selected channels.